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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

TURNER, HAENKE AND HUBBARD GLACIERS                 113
From the cairn built in 1909 between Hubbard and Variegated Glaciers (Photo. Station F, Map 8), it was plain in 1910 that one point near the center of the glacier had advanced since 1909 perhaps several hundred feet, that the dirty projecting cliff had advanced slightly, and that crevassing in the non-tidal southeast edge of the glacier had increased somewhat. The same was observed from near the site of Gilbert's beach station, close to the ice edge (Photo. Station E, Map 3). The area of black crevassed ice bared by June, 1910, and of cracking had not increased so much near the head of the stream between Hubbard and Variegated Glaciers as close to the tidal portion, though even here the additional crevassing was not remarkable. The surface of the margin of the glacier still showed many minor hummocks of ablation moraine that were present in 1909. The dirty tidal cliff was a little less debris-stained than eleven months before. All in all, therefore, although there had been noticeable change, the transformation was not remarkable. One could say distinctly that advance had continued since 1909, but it was no such advance as took place in Atrevida, Variegated, Haenke, and Marvine lobe of Malaspina Glacier between 1905 and 1906. Indeed, with the specific measurements of retreat shown in some points of the ice front (Map 3), it is thought possible that the advance initiated in the southeast portion of the glacier between 1906 and 1909 was nearly over in 1910.
The advance of the northwest portion of the glacier which began earlier seemed to be continuing more vigorously. Iceberg discharge from the front of Hubbard Glacier was probably less active in June, 1910, than in the previous July. More floating ice was present, but that was thought to be due chiefly to another cause.
Condition in 1913. Because of the delay incidental to the detention of the International Geological Congress ship on the newly-discovered reef near Osier Island in September, 1913, the junior author was unable to reoccupy any of the photographic sites established in earlier years. It was clear, however, that the slight advance of Hubbard Glacier in 1909-10 was practically over before 1913. No part of the ice front had advanced significantly and the western and southeastern margins seemed to have retreated slightly. Iceberg discharge was much less active than in 1910, a fortunate circumstance to which may be ascribed the fact that no more damage was done to the vessel during her half day's stay upon the reef in front of Hubbard Glacier.
Significance of the Advance. The complex history presented by the Hubbard Glacier corresponds, in a way, with that of the Turner, and the interpretation placed upon it is the same. It does not follow, of course, that the rather deliberate advance of the northwestern arm from 1901 to 1910 following the retreat of 100 to 200 feet between 1890 and 1899 and of 700 to 1000 feet between 1899 and 1901, is the only response that this part of the glacier will show to the effects of earthquake shaking. It may be that the advance was merely the result of climatic influences, or of an impulse due to earthquake shaking imparted by one or a small number of tributaries, and that a still greater forward movement is yet in store. It would be interesting and quite unexpected if so large a glacier .gave such a. weak response to the cause which pushed the front of the far smaller neighboring Haenke Glacier forward nearly a mile, or if the north arm, which is so active, should fail to respond strongly and advance vigorously later, as it did weakly in 1909-10. It is by no means an impossibility that, under the influence of such a thrust, Hubbard Glacier front might be pushed forward two miles across the fiord to the mountain side behind Osier Island, making Russell Fiord into a lake once more.